For years Amidon was pretty much the only place hams bought ferrite and
powdered iron cores. A different company sprang up a few years back,
composed of some former Amidon associates as well as former Amidon
employees, and they are selling the same things. (Their reasons for going
out on their own involves, I believe, discontent with their relationships
with their former company, something which is hardly uncommon in the
business world.)

The name is Bytemark, or more properly CWS Bytemark, since it merged with
CWS a while back.

The URL is http://www.bytemark.com/ and the site has a lot of technical info
on the toroids.

At least one of them is a ham, Tracy Markham, N4LGH, who was the driving
force behind the original Bytemark. He's a homebrewer and was active on the
QRP mail reflector for a few years.